Slow differential rotation of the Earth's inner core indicated by temporal changes in scattering
Article Abstract:
An analysis of scattered waves recorded in Montana from two closely situated nuclear tests at Novaya Zemlya, USSR, in 1971 and 1974 indicates changes in scattering. These changes suggest an inner-core differential rotation rate of 0/15 degrees per year.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 2000
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Fine-scale heterogeneity in the Earth's inner core
Article Abstract:
An investigation of 12 earthquakes and four nuclear explosions in the distance range 58 degrees to 73 degrees has sampled four distinct regions of the inner core. The 200 seconds of observed ground motion is attributed to inner-core scattering (ICS). The stack from each event shows ICS energy, but only by stacking all 16 events together is it possible to find a relatively smooth envelope. The ICS energy reported in this research could play a role in determining the rotation rate of the inner core with high precision.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 2000
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Evidence for partial melt at the core-mantle boundary north of Tonga from the strong scattering of seismic waves
Article Abstract:
The core-mantle boundary (CMB) is the lower bound on mantle convention, and the lowermost mantle must underlie at leas a thermal boundary layer. There may be a chemical heterogeneity just above the CMB. The lowermost mantle has two types of seismic structure, layering in P and S wave velocities and weak fine-scale heterogeneity from scattered waves, preceding the seismic phase PKP. Observations of scattered PKP waves needing large velocity perturbations close to the CMB are presented. Their position is noted beneath low-velocity lower mantle and close to a patch showing slow basal P velocities.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1998
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